Wireless mobile communication can enhance a maximum data rate which can be provided through a frequency bandwidth, multiple antennas, an interference cancellation technique, and the like.
It is expected that the wireless mobile communication will evolve in a way to greatly increase a bandwidth by using a medium frequency and an ultra high frequency, instead of a frequency band that is currently used, and thus to greatly enhance the data rate by utilizing antennas which are several times to several tens of times larger than the data rate of current wireless mobile communication.
Since an interval at which the antennas interfere with each other becomes shorter when a transmission frequency band becomes higher, the number of antennas per unit area may be greatly increased, and as a result, synergy may be generated to enhance the data rate.
However, since linearity of an electromagnetic wave becomes stronger when the transmission frequency band becomes higher, and as a result, reflection, diffraction, and dispersion may be weakened. Therefore, there may be a challenge to secure the coverage compared with a current wireless mobile communication base station.
That is, when the current wireless mobile communication base station is installed in a specific region, a terminal may receive a radio signal at a predetermined level or higher even in a region which a base station antenna does not directly face through the reflection, the diffraction, and the dispersion of the electromagnetic wave in non line-of-sight (NLOS). However, as the transmission frequency band becomes higher, the strength of the received radio signal is drastically reduced.
In general, when the number of antennas of the base station increases, the quality of the received signal of the terminal is enhanced and when a plurality of independent data may be simultaneously transmitted and received, and as a result, the data rate is enhanced. However, when the transmission frequency band becomes higher, the linearity of the electromagnetic wave is enhanced, and as a result, the quality of the received signal in the terminal is further enhanced, but spatial multiplexing using multiple ranks to transmit the plurality of independent data becomes difficult.